The proposed research programs are designed to gain insight at the molecular level of control processes which regulate gene expression, virus replication and cell growth--primarily in mammalian cell-virus systems, and with an emphasis on mechanisms of transcription and translation. Specific areas of research include: Optimization of in vitro systems for high fidelity translation of viral mRNA; coupling of viral transcription-translation processes in vitro; development of suppressor strains of animal cells; mechanism of L-histidinol inhibition of protein synthesis; de-acylation as a control mechanism; the role of poly(A) in mRNA processing; mechanism of viral control of cellular protein synthesis; role of initiation factors in translation; regulation of mRNA translation by translational control RNA (tcRNA); cleavage of viral polyprotein in vitro; interferon action - the role of membrane-bound RNase; the lethal action of interferon on cells; cell killing by viruses and by double-stranded RNA; mechanism of intrinsic interference; RNase-inhibitors as regulators of cell growth an function; use of nanomelic mutants in differentiation of chondrocytes; control of chondrocyte phenotypic expression in vitro; role of cell surface proteoglycans in differentation; characterization of mRNA for tubulin; control of redundancy of rRNA cistrons; BUDR and redundacy of rRNA DNA; mechanisms regulating nucleolar transcription; action of RNA polymerase II as an auto repressor; selection of ts-mutants in RNA synthesis.